/Engine/Source/Runtime/Engine/Classes/Engine/AssetManager.h
Changes the bundle state of all loaded primary assets. Only assets matching OldBundles will be modified You can wait on the returned streamable request or poll as needed. If there is no work to do, returned handle will be null and delegate will get called before function returns.
Streamable Handle that can be used to poll or wait. You do not need to keep this handle to stop the assets from being unloaded
virtual [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FStreamableHandle](API\Runtime\Engine\Engine\FStreamableHandle) > ChangeBundleStateForMatchingPrimaryAssets ( const [TArray](API\Runtime\Core\Containers\TArray)< [FName](API\Runtime\Core\UObject\FName) > & NewBundles, const [TArray](API\Runtime\Core\Containers\TArray)< [FName](API\Runtime\Core\UObject\FName) > & OldBundles, FStreamableDelegate DelegateToCall, TAsyncLoadPriority Priority )